Arbitration — Waiver — Purchaser’s dispute with motor vehicle dealer — Trial court properly determined that legally binding agreement to arbitrate existed, that dispute fell within scope of that agreement, and that defendant had not waived its right to arbitrate — Defendant’s failure to pay American Arbitration Association fees several years earlier in a different arbitration proceeding, which resulted in AAA’s refusal to arbitrate the current dispute, did not amount to waiver of right to arbitrate in this case involving different purchaser and different contract; and defendant promptly took necessary steps to resolve earlier dispute with AAA so that it could arbitrate current dispute — Plaintiff’s reliance on AAA Consumer Arbitration Rules is unavailing where rules were not expressly incorporated into contract at issue — Further, unavailability of AAA to conduct arbitration does not negate agreement to arbitrate, which provided that purchaser could choose AAA “or any other organization to conduct the arbitration subject to” dealer’s approval